The discussion of the Williams sisters' technique in Pro Player Talk really surprised me. Technique is important for several reasons:
1. Injury prevention: biomechanically sound practices such as , don't lead with elbow on 1H BH, don't hold arm straight on FH.
2. Duplication and consistency that comes from having technique: being able to hit shots that have a high predictability of pace, spin, and depth.
3. Footwork: Maintenance of balance when hitting, maintenance of court position without making it easy to hit behind you.
4. Biomechanical efficiency: hitting shots with maximum effect you want (power or spin) for the most minimal effort possible.
5. Unorthodox techniques to accomodate injuries and unusual capabilities. Such as Mac's serve or Bertasegui's hitting with the same face of the racquet.

I just did this off the top of my head. Additions, disagreements, corrections? What say ye?

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"In theory, there is no difference between practice and theory. In practice, there is." Lawrence Berra